1. Field of the Invention
The present invention relates to a process for producing an ink jet recording head.
2. Description of the Related Art
U.S. Patent Publication No. 2009/0095708 discloses a production process of an ink jet recording head. In U.S. Patent Publication No. 2009/0095708, a nozzle structure having a liquid flow path is formed on a front surface (first surface) of a substrate, and a film which will become a mask material for forming a common liquid chamber (ink supply port) for supplying an ink is then formed on a back surface (second surface) of the substrate. After this film is then used to form the common liquid chamber, an ink supply port (independent ink supply port) is independently formed within the common liquid chamber by photolithography.
The etching mask on an etching start surface of the back surface of the substrate is formed by photolithography using a photomask, and alignment between the substrate and the photomask is controlled in the following manner. That is, an image of a substrate side alignment mark photographed from the upper surface side (front surface) of the substrate is superimposed on an image of an alignment mark of the photomask photographed from the lower surface side (back surface) of the substrate by image processing. The position of the photomask is then controlled in such a manner that their alignment marks are aligned with each other.
Japanese Patent Application Laid-Open No. 2005-109122 discloses a process for forming on a substrate an alignment mark used in alignment between the substrate on which a plurality of devices are formed and a photomask for masking a resist applied to the substrate. More specifically, it is disclosed that the alignment mark formed on the substrate is formed in a region to be removed from the substrate in a subsequent step in the portion of the substrate on which the devices are formed, i.e., in a region where an electronic circuit is not formed.
However, when the nozzle structure on the front surface (first surface) of the substrate is coated with a protective film for protecting the circuit upon forming a pattern of the independent supply port on the resist, and alignment between the substrate and the photomask is conducted through the nozzle structure and the protective film from the front surface side of the substrate, alignment accuracy may be lowered in some cases by the influence of the film because the alignment is conducted through the nozzle structure and the transparent protective film.
An object of the present invention is as follows. That is, the object is to provide a process for producing an ink jet recording head, by which alignment can be conducted with high accuracy without being affected by a nozzle structure and a film such as a protective film which are formed on a front surface of a substrate and without adding any step while retaining appropriate strength.